I'm not an expert but I've read that relocating them is hard because they're so territorial and there's not like an abundance of wilderness left to put him. He probably would have been killed by a younger mountain lion by now if he was in a more wilderness territory.

There was the thought maybe he'd cross back to the Santa Monica mountains, maybe a female would cross over to Griffith park.

He wasn't a problem until the very end, then he was caught and found to be in rough shape, probably suffering. FWIW, coyotes kill more pets but are afaik only killed when they get too familiar with humans or are aggressive.

https://abc7.com/chihuahua-killed-granada-hills-caught-on-vi...